Riyadh is in Saudi Arabia and is currently on UTC+3. Its time zone is Asia/Riyadh.
Riyadh does not observe daylight saving time. It stays on UTC+3 all year, so the difference to any other place that also holds a fixed offset never changes.
The weekend in Riyadh falls on Friday and Saturday. A working day of 9:00 AM to 6:00 PM is the assumption used on the board.